You shouldn't "trust" as a basis for security or privacy. Eg for protonmail, Proton can still read your incoming emails if they arrive unencrypted; the only way to avoid that is to send E2EE email, which unfortunately most email is not. You should assume that if they can, then they are.

If you have to use proton for whatever reason (can't afford to pay to self-host things, don't know how to and don't have time to learn, etc), it's perfectly fine for everyday use for things that are not particularly sensitive ie you don't have a highly resourced state actor actively trying to obtain that data. Just always keep the first thing in mind. Too many people treat anything that calls itself "encrypted" as a silver bullet.